Field of the Invention
The present invention relates to an improvement in the performance of liners called "wet and compressed" liners, installed in the cylinder blocks of internal combustion engines and particularly Diesel engines with precombustion chambers.
The advantages inherent in the use of wet and compressed liners installed in cylinder blocks have long been known (simplification of the casting and machining of blocks, whether of cast iron or aluminum; the possiblity of using a cylinder block of aluminum cast under pressure, without encountering the difficulties of casting borings and those caused by friction of pistons in the aluminum; the possibility of employing a cast iron more suitable in terms of friction and cast by centriugation to improve the constancy of its characteristics; great ease in replacing liners and pistons in case of repair without tearing down the motor block and without reboring, etc.).
The liners called "suspended", unlike those called "compressed", have on their upper part, a cylindrical flange for their support in the cylinder block. This entails large interaxial distances between cylinders and vaults or reinforcements in the intercylinder plane to avoid the depression of the liner when tightening down the cylinder head. Further, the cooling of the upper part of the liner is from beneath the support of the flange, which reduces its effectiveness in the hottest zone.
The liners called "compressed" do not involve this construction, their support being at the bottom of the cylinder block water jacket. The absence here of a flange thus permits better cooling of the upper part.
O-ring sealing systems permit then, the reduction of the surface of support of the liner as a function of the allowable value of the support pressure limit, called that of caulking, which depends on the resistance of the materials in contact.
Flats can be provided on the liners to diminish the interaxial distance between cylinders and, consequently, the length of the motor. This type of liner works under compression, in the portion corresponding to the distance between its lower support and its upper face, when the cylinder head is tightened down.